---------------------
POST				 |
---------------------
	public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");
	OkHttpClient client = new OkHttpClient();
	String post(String url, String json) throws IOException {
		RequestBody body = RequestBody.create(JSON, json);
		Request request = new Request.Builder().url(url).post(body).build();
		Response response = client.newCall(request).execute();
		return response.body().string();
	}